When a simple demonstration of resonance in a forced oscillation system proved that resonance does not exist

Abstract

Students in an introductory musical acoustics course attempted to recreate a simple forced oscillation system to verify its resonant frequency. The procedure followed ideas and instructions found in a YouTube video from Animated Science to show resonance. This was tested by the instructor prior to the experiment, who found it to be straightforward to assemble and to make the appropriate measurements. The calculated frequency was found to be within 2.5% of the experimental value. The students were given two identical springs, each with a spring constant of 30 N/m and a 100 g mass, as well as a function generator and apparatus needed to connect the system. The video shows the mass suspended between the two springs with one end driven by a function generator while the other end is fixed. A meterstick was placed behind the mass spring system to get a rough estimate of the peak amplitude. 6 separate groups of 3 students each tried to assemble the system as shown. Not a single set-up worked as it did in the video. The reasons for this were as varied as the number of groups doing the experiment. The experiment was refined over several years into a well-executed experiment.